AMD Unleashes the 990FX: Paving the way for Bulldozer

Word of the AMD 990FX chipset first came around the end of last year. Speculation was brisk as to what new features it would bring, and when exactly it would help to usher in the age of Bulldozer to the world. Most thought that it would be a shrink of the then current 890FX, and the new SB950 southbridge would have improvements to the SATA 6G controller, as well as a native USB 3.0 implementation. Today we finally get to see the reality of the situation. It is not groundbreaking, nor is it altogether exciting, but it is certainly interesting.

The 990FX and SB950 chips are identical to the previous 890FX and SB850. They are the same silicon. For those hoping for new technology will be disappointed. But all is not lost! AMD did increase the HyperTransport specification from 3.0 to 3.1, which allows the HT bus to run at 6.4 GTPS as compared to the older 5.2 GTPS. This is in place to allow the upcoming Bulldozer chips to run the northbridge portion of the chip up to 3.2 GHz, and to give the CPU more bandwidth between the different busses on the board (eg. SATA, USB 3.0, and PCI-E connections).

The other advance, but one that is not covered as of yet due to there not being any Zambezi/Bulldozer based chips to test on, are some improved power characteristics. AMD has changed and improved the power specification, so it is a more efficient unit overall. This sounds like it is needed due to how the new Bulldozer chips handle turbo speeds and power gating. We should see some efficiency improvements with current CPUs, but these are in the range of a couple of watts. These results are measurable, but simply not meaningful for most users.

Two households, both alike in dignity...

At the end of the day, the reason that AMD decided to rebrand these chips as the 900 series is to make crystal clear what motherboards support the upcoming Bulldozer processors. While some motherboard manufacturers have enabled Bulldozer support through beta BIOS programs, it is still unclear how these boards will handle all of the features of that upcoming CPU. I am pretty sure most of the high end 890FX boards will work flawlessly with the new chips, but for quite a few users out there we probably should expect some confusion. AMD’s stance is that if a user wants a Bulldozer CPU, they should get a AMD 900 series of motherboards.

The most interesting update to this chipset is of course the SLI support. NVIDIA has finally relented, and allowed their manufacturing partners to include SLI support on the latest AMD chipset. It has been over two years now since NVIDIA launched the 900 series of AMD based chipsets. In the intervening time we have seen the introduction of SATA 6G and USB 3.0 on the AMD side, as well as some nice improvements in overclocking and power consumption. Unfortunately, the 980a boards currently available for AMD processors are just not that impressive when compared to what was available at the 890FX launch last year. Apparently with the specter of Bulldozer hanging over the market, and a pretty consistent call from reviewers and users alike, NVIDIA has given its blessing for multi-GPU goodness with their cards on the new 900 series of chipsets. There is one stipulation though; SLI is available only to those motherboard manufacturers who previously licensed the technology on their Intel P67 motherboards. So, we will see a handful of 990FX motherboards that do not officially support SLI. This is not the case for the two contenders we are looking at today.

Generally speaking, and you would have to consult the individual manufactures user manual for the specifics. But particularly on the older (same?) 890FX boards, specifically the MSI890FXA, there are only two true electrically x16 slots.

When running in a x16/x16 configuration, one of the slots is disabled (if memory serves it was the lower most slot), and the middle "x16 size" slot, which is physically only x8 electrically, would only being allowed x4 bandwidth.

Now, if you populate the lower most "disabled" slot (x8 electrically), it will be given x8 bandwidth, and the above true x16 slot would be reduced to a x8 as well, as the lanes on those slots are split. Which is why in a true x16/x16 configuration, it is effectively disabled.

So it is completely dependent on how the manufactures split the lanes on the board, and what slots share those lanes when split. And MOST (not all) manufactures usually give a comprehensive slot population chart to explain how it will work. But on average with a x16/x16 configuration, there will always be one remaining x4 electrically, x16 physically slot.

Usage of the slots and add in cards is obviously going to differ by individual. The MSI board does give slightly more flexibility in that you can use both the PCI slot and 1x PCI-E slot even when in Crossfire or SLI. So yeah, their layout is better overall than the Asus board. Then again the DIMM slots on the MSI board are physically closer to the socket by a decent amount, which is going to cause headaches for some folks.

But in terms of a better overall board in testing, Asus has the edge here.

Unless you must have a 1x PCI-E slot I see no reason to buy the MSI board over the Asus one unless there is a large discrepancy in price.

I have nothing against MSI, heck my backup PC uses a P55-GD65 and a MSI 4870x2 which I'm using to type this message, but I was sorely disappointed by the 990FXA-GD80 given the stellar performance of the 890FXA-GD65.

I think a lot of the issues with the board are related to the BIOS in one way or another. ClickBIOS II is supposed to be a major upgrade, and should feel a whole lot faster than the current one. I would imagine that overclocking the HTT bus will also show improvements, as well as the random network issues that have been reported for this board by a handful of reviewers.

Glad you are having a good experience with your board though. You are right, it is far from being a bad board, but it just didn't quite match the level of its predecessors and competition.

I bought the Sabertooth last week.
But I have a problem with AI Suite II. It won't start, generating an APPCRASH on my Windows 7 Ultimate SP1 (x64).
I tried to uninstall it, but it leaves a bunch of entries in registry and two related services still running...

Did you run the installer from the CD, or download it from the Asus website? I have found that often it is preferable to download that version, as sometimes the ones on the CD are more than a little old and could have poor support with new products. This is something of an issue with most motherboard manufacturers.